Computer-aided design (CAD) software allows a user to construct and manipulate complex three-dimensional (3D) models. A number of different modeling techniques can be used to create a 3D model. One such technique is a solid modeling technique, which provides for topological 3D models where the 3D model is a collection of interconnected topological entities (e.g., vertices, edges, and faces). The topological entities have corresponding supporting geometrical entities (e.g., points, trimmed curves, and trimmed surfaces). The trimmed surfaces correspond to respective topological faces bounded by edges. Hereinafter, the terms vertex, edge, and face will be used interchangeably with their respective, corresponding geometric entities.
A design engineer is a typical user of a 3D CAD system. The design engineer designs physical and aesthetic aspects of 3D models, and is skilled in 3D modeling techniques. The design engineer creates parts and may assemble the parts into a subassembly or an assembly. A subassembly may also consist of other subassemblies. An assembly is designed using parts and subassemblies. Parts and subassemblies are hereinafter collectively referred to as components.
During the design process, an engineer may wish to analyze the motion of a 3D design of a model to evaluate the real-world requirements and performance of the product being designed. Such an analysis may be executed by an engineering simulation process, such as SOLIDWORKS® Motion and SOLIDWORKS® Simulation, both available from Dassault Systemes SolidWorks Corporation of Waltham, Mass., and both of which use the CAD model data to set up and execute motion and simulation studies.
Motion analysis is one of the most important and basic analyses that is executed during the design of a real-world object. While motion analysis is very useful for providing insightful numerical results, there is a very stringent assumption made by analysis programs about the rigidity of parts in the assembly. Usually, motion analysis of a mechanism is done under the assumption that the parts in the assembly are rigid (i.e., the parts do not change size or shape).
However, when motion analysis is repeatedly performed, for example within another analysis process, often a need exists to resize the geometry of the parts involved in the motion analysis. For example, when a user wants to optimize the design of a mechanism to reduce a tracking error (i.e., the difference between the desired trajectory and the actual trajectory traced by the tracking point of a mechanism), rigid body simulation needs to be performed repeatedly such that in every iteration of the optimizer the rigid parts are resized to different dimensions and the tracking error is computed once again. Using conventional rigid body models becomes difficult in such a case because the dimensions of the parts keep changing. Generally, a user's only option is to discard previously built rigid body models and build new ones in every iteration cycle of the simulation process, where the new rigid body models have resized dimensions of individual parts. This is inefficient and time consuming.
A method and system that does not require a user to redesign one or more parts multiple times in order to run a motion analysis process in which rigid parts need to be resized would enhance the capabilities of CAD and computer-aided simulation systems by speeding up the process in which a model may be designed and analyzed.